hepworth



(No Model.) a Sheets-Sheet 1. J. HEPWORTH.

VARIABLE EXPAN$ION GEAR.

Patented Aug. 2, 1887.

W ww N PETERS. mammo ram, Washinghm. n. a

(No Model.) 3 Sheets-Sheet 2. J. HEPWORTH.

VARIABLE EXPANSION GEAR.

No. 367,713. Patented Aug. 2, 1887.

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(No Model.) 3 Sheets-Sheet 3.

J. HEPWORTH.

VARIABLE EXPANSION GEAR. No. 367,713. Patented Aug. 2, 1887..

. R A R u H. R v A r H g A R g 7% fi O Q N F F m H N a 5* s 5* a e) UNITED STATES PATENT OFFICE.

JOHN HEPVVORTH, OF MONTREAL, QUEBEC, CANADA.

VARIABLE-EXPANSION GEAR.

SPECIFICATION forming part of Letters Patent No. 367,713, dated August 2, 1887.

To all whom it may concern:

Be it known that I, JoIIN HErWoR'rH, of the city of Montreal, in the district of Mentreal and Province of Quebec, Canada, have invented certain new and useful Improvements in Variablellxpansion Gears; and I do hereby declare that the following is a full, clear, and exact description of the same.

This invention covers certain improvements on the "ariable expansion gear for which I have already filed application for Letters Patent of the United States, under the Serial No. 227,148; and it consists in certain modifications of the construction therein shown and described, which will render the invention applicable to locomotives and other engines which require to have steam admitted at from zero to three-fourths of the stroke.

The construction of the several parts-via, the plate formed on the main-valve stein with foot on lower side, four-armed piece pivoted to plate in its center, connected at its upper end with stem of riding-valve and at itslower end by springs to fixed points on the engine, and the stops pivoted to the cross-arms of fourarm ed piece-is as described in the application above referred to, and needs no modification.

The main modification oftheinvention isthat the doubleerank, to which the ends oft-he tripping-levers are pivoted, is not simply pivoted to a fixed point on a standard and operated solely by the governor and for the regulation of the distance apart of the tripping-levers, but has a positive motion imparted to it by means of a swinginglinlgto which it is secured and which is pivoted to some fixed point,and connected in a locomotive by another link to the crosshcad; butin a horizontal stationary enginethis link is made to move by means of a separate eccentric, or it may be made to do so by connecting with the n1ain-valve eccentric through a bellcrank. The means by which the link is made to travel differ according to the type of engine to which this cutoff is applicd,and the swinging link may be connected to any moving part of the engine that gives a lateral travel to the double crank,which coincides with that of the crosshead of theengine. This positive motion of the double crank will also impart to the tripping-levers a positive motion, and as the double crank is thrown in either direction by the movement of the cross- Application filed April 5,1887. Serial No.233flil0. (Nomodeh) Patentcdin Canada February 14, 1887, No.25,998.

head or through the eccentrics, as the case may be, the tripping-levers are brought to meet the stops and act upon them to disengage them in turn from the foot, as described in the pending application.

The regulation of the point at which the cutoff shall take place is in the stationary engine effected, as before, through suitable connections, automatically by the governor, and isin the locomotive under the control of the driver, who operates by means of a rod connected with the expansion lever secured to the expansionbar on which the double cranks are attached.

For full comprehension ol'the i n vention, reference must be had to the annexed drawings, forming part of this specification, in which- Figure 1 is a side view of the invention as applied to a locomotive; Fig. 2, asimilar view, enlarged, of operating parts; Fig. 3, an end View of same; Fig. 4, a view showing parts connected to a single eccentric, and Fig. 5 a view of same when operated from a double eccentric.

, Similar letters of reference indicate like parts.

As the construction and arrangement of the cylinder, piston, steam-chest, main valve, and ridingvalve differ in no points from types of those now in use, no further allusion will be made to them.

A is the standard or bracket, secured to any fixed point'on the engine, 13 being, as before, the double crank, and G G the tripping-levers, pivoted to A, both these to be hereinafter more particularly alluded to, and O G links.

D is the main-valve stem, 1)" the extension on same, D the step, E the cross or four-armedpiece, F F stops pivoted to side arms of same,

G riding-valve stem, H the riding-valve, and I J J springs, all constructed and arranged as set forth in pending application.

In a locomotive, and when the double crank receives its mot-ion from the cross-head, the double crank B is secured to a swinging lever, L, pivoted at Z to the standard, extended downward, and connected by a link, L, with the cross-head. In this case, and in others with double cylinders, the regulation of cut-off is effected through the expansion-bar M, passing through slot a in standard, this being open ated by a rod, llf, through expansiolrlever M.

In a stationary engine, where the motion to the double crank is imparted by means of an eccentric, then the swinging lever L will be made much shorter and the stud that carries the double crank will also connect with one eccentric or bell-crank.

In a double eccentric the rod 0 will be connected directly with that one which does not impart motion to the main-valve stein.

In Figs. 4 and 5 an extension, B, is shown formed on the double crank at right angles to it, and connected by rod X with the governor.

The operation of the parts will, as regards the action of the four-armed piece E through the springs J J on the riding-valve H, be similar to that described in the pending case; but the movement (simultaneously with that of the cross-head) of the double crank B, actuated by the swinging link L, which is operated from the cross-head,either directly or by compound motion, through the eccentrics, gives to the tripping-1evers positive motion in either direction, so that each of these is brought alternately in contact with one of the stops F or F, knoeking it off the step I) and releasing the valve, as before described. The motion of the tripping-levers is at first slow, but gradually increases in speedas the piston advances toward the middle of the stroke, at which time the main-valve stem has ceased to advance,so that all degrees of expansion from one twelfth to one-third of the stroke are made while the valve is traveling, and from one-third to twothirds of the stroke while the valve is almost stationary. The difference in the means for imparting to the swinging link L motion corresponding to that of the cross-head are simply due to the varying types of the engines before mentioned, and devised to accommodate them; but if. absolutely desired the swinging link could be connected on a stationary engine with the crosshead, and in some types of locomo tives could be worked from the eccentrics.

I am aware of the Patent No. 324, 964:,granted to And. J. Stevens, August 26, 1885; but the invention therein described has reference to double main valves and corresponding valvestems.

Having thus described my invention, I beg to state that what I claim is as follows:

1. In a steam-engine, the combination,with a four-armedlever pivoted to and moving with the main-valve stem,connected at one end with the stem of the riding-valve and at the other by springs with fixed points on the engine, and carrying on its cross-arms stops locking the lever in place, of tripping-levers pivoted centrally to fixed points, a double crank to which the ends ofsuch tripping-levers are pivoted, a swinging link carrying such double crank, and means for imparting thereto the motion derived from the cross-head, all sub stantially as herein set forth, and for the purposes described.

2. In a steanrenginchaving double cylinders, the combination, with the double cranks B, to which ends of tripping-levers O O are pivoted, ol'swinging levers connected by links with the cross-hcads, and expansion-bar actuated by lever and rod passing through such swinging levers and carrying on its ends the cranks B, all substantially as and for thepurposes described.

The combination, with the double crank 13, connected by links with tripping-levers O C, and means for releasing at regulated intervals the riding-valve, of thcswinginglever L, pivoted to frame, carrying crank B, and con? neeted by rod 0 with eccentric on crank-shaft, all as and for the purposes herein described.

JOHN HEPWORTH.

\Vi t n esses:

O'r'ro EDw. Evans, YVM. PQMOFEAT. 

